Fitzsimons is an employee of the British company ArmorGroup, formerly chaired by one-time foreign secretary Malcolm Rifkind. Like other private security firms, ArmorGroup felt the effects of the killing of 17 Iraqi civilians by contractors with the US company Blackwater, now Xe, in 2007. The immunity enjoyed by foreign contractors since the toppling of Saddam Hussein was removed and Fitzsimons will be the first westerner to face a trial in Iraq for murder.

In the aftermath of Blackwater, there was a drop in the use of private security firms and ArmorGroup will be hoping it does not suffer the same fate as the US company, which eventually lost its licence.

It has been a difficult couple of years for ArmorGroup as business in Iraq has dropped off following the boom in work during the early stages of the occupation: as reconstruction spending and troop numbers have declined, there has been less need for private security companies.

The declining prospects in Iraq led the company to accept a takeover last year by rival G4S, the largest security services company in the UK. ArmorGroup is currently the largest convoy protection company in Iraq and in 2007 conducted almost 2,400 missions, almost 30% of registered convoys there, according to the G4S website, which boasts: "We are proud to have the highest successful delivery rate of any company in the highest threat areas of Iraq".

The embassy and convoy security specialist has a significant presence in Afghanistan, where its operations have also come under scrutiny, albeit for different reasons.

In June this year, US state department officials and representatives of ArmorGroup's American affiliate were grilled by the Senate subcommittee on contracting oversight over allegations of waste, fraud, and abuse relating to the company's contract to provide security at the US embassy in Kabul.

The deputy assistant secretary of state, William Moser, told the subcommittee the state department would renew its agreement with ArmorGroup North America "despite lingering concerns with weapons shortages, the company's training programmes and the poor English language skills of some guards, mostly Nepalese ghurkas", the Washington Post reported.